1. Field of the Invention
The present invention relates to a cooled pellet making machine for producing resin pellets from a strand by cutting the strand with a rotary cutter and a fixed blade. The strand is molded in a linear configuration utilizing a die mounted on a head of an extruder.
2. Description of the Prior Art
Conventionally, in this type of pellet making machine, pellets are produced by cutting a strand which has been cooled. However, resin materials may stick to the rotary cutter and the fixed blade since the temperature of the rotary cutter increases during a cutting operation, thereby impairing the cutting effect which may result in pellets of non-uniform sizes. Furthermore, static electricity is generated which causes the pellets to adhere to each other.
Therefore, a solution has been proposed, wherein a strand is caused to pass through a cooling water layer and when cooled sufficiently, the strand is cut into pellets by means of the rotary cutter. The hot resin pellets are thrown into a cooling water tank following the cutting operation.
However, when the strand cutting operation is started, the pellets may not be uniform in shape which may lead to rejectable products.
In view of the above-described background, the inventor of the present invention has proposed a solution in U.S. Pat. No. 5,186,959, in which cooling water is poured into and allowed to circulate through a rotary cutter in order to prevent the rotary cutter from generating heat and causing the resin material to adhere to the surface of the rotary cutter.
In the prior art approach and the like, when the strands are of relatively large diameter, the strands are subject to relatively less adverse effects as a result of deformation which occurs under expansion and bending etc. even if the fixed blade and the fixed support table are heated in a pellet making operation of making pellets. However, a recent trend is to produce super mini-sized pellets. Strands in diameter ranging from 0.3 mm to 0.7 mm are currently cut to produce super-mini sized pellets.
As a consequence, in the case of a strand having an especially reduced diameter, strands which have been fed through the feed roll may soften due to the heat in front of the rotary cutter, or fluctuate and vibrate when they are subject to a slight wind pressure or vibratory motion from the electric motor. Thus, the strand may be cut in irregular configurations, thereby preventing precision cutting and resulting in worthless products of non-uniform size.